Dont get databse my connection string

Question

i creating exe file of my c# window application but my client machine i dont get databse
my connection string is
 conn = new SqlConnection(@"Data Source=.\sqlexpress;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\DATA\Mahallu.mdf;Initial Catalog=net;Integrated Security=True");